Definitely do an away if you can(in June/July/August. You can possibly get another LOR if you do it early enough from a well known ophthalmologist at another program to have in your application. This may open a few more doors for interviews. Literally programs will grant an interview based off the fact that someone in the program who saw your application personally knew the letter writer in some capacity. Also, if you do it a program that you think you may want to be a part of, you can get another interview, which always increases your match possibility. In addition, although you may want to stay at your program, it is never a guarantee that your program will rank you high enough to match there, especially if there are others in your class going into ophthalmology. In ophthalmology a back-up plan is always good to have. Why waste your time doing an ortho rotation when you could be auditioning at an ophthalmology program. Honestly once you get into the ins and outs of ophthalmology as a fourth year, the work becomes second nature and an audition can be more pleasurable than a "chore". Matching is no guarantee. Just check out the threads on people who did not match with stellar resumes.
Programs do not like filling their residency with only residents from their medical school, so no matter how much you love your program, they may have other plans for ranking applicants when rank order lists are due. One more interview from an audition(which I assume they will like you) can make the difference between matching and not matching. The last thing you want to do is regret not doing another away in favor of doing some random rotation for fun.
Personally I do not see the point in doing orthopedic surgery or urology or whatever else thats intensive unless they really excite you or your school makes you for some reason. You worked your tail off to be a competitive applicant for ophthalmology, so don't waste your time getting up for 5:30 am rounds to learn how to fix a humeral fracture or watch a transurethral resection of the prostate as a fourth year medical student. Waste of time and energy. Unless, of course, learning that information excites you. Save some easy rotations/free time second semester. Get your bare minimum requirements done and relax/travel/party etc. This may be the last time you can "relax" for any extended period of time for a very very very long time.
